The Wechsler Adult Intelligence Scale (WAIS) has been used extensively to study impairment across a range of cognitive domains in schizophrenia. However, cognitive performance among those with the illness has yet to be examined using the newest edition of this measure. Hence, the current study aims first, to provide WAIS-IV normative data for Canadian individuals with schizophrenia of low average intelligence; second, to examine schizophrenia performance on all WAIS-IV subtest, index and general intelligence scores relative to healthy comparison subjects; and third, to revalidate the pattern of impairment identified in this clinical group using the WAIS-III, where processing speed (PS) was most affected, followed by working memory (WM), perceptual reasoning (PR) and verbal comprehension (VC). The WAIS-IV was administered to outpatients with schizophrenia and their performance compared with age, gender, and education matched controls. WAIS-IV schizophrenia performance data are provided. Analyses revealed significant impairment on several tasks, including the new Cancellation subtest and the VC supplemental subtest, Comprehension. At the index score level, group differences in PS were significantly larger than those observed in all other cognitive domains. Impairments were also observed in WM amid relatively preserved performance in VC, thereby confirming the pattern of impairment identified using the WAIS-III.
Keywords: Wechsler Adult Intelligence Scale; cancellation; cognition; processing speed; schizophrenia; verbal comprehension; working memory.